Liquid agitating device



OC- 18, 1966 TETsuYA sATo ETAL 3,279,765

LIQUID AGITATING DEVICE Filed April 27, 1964 INVENTORS 55 esuy 6x50,

f/aswga, 75m/mwah ORNEYS United States Patent O 3,279,765 LIQUID AGITATING DEVICE Tetsuya Sato and Masuya Tsukamoto, Shingu-cho, Ibogun, Hyogo, Japan, assignors to Kabushiki Kaisha, Teikoku Denki Sesakusho, Osaka, Japan, a corporation of Japan Filed Apr. 27, 1964, Ser. No. 362,612 Claims priority, application Japan, Mar. 3, 1964, 39/ 11,887 2 Claims. v(Cl. 259-106) The present invention relates -to a liquid agitating device adapted for use in chemical industry for the purpose of agitating liquids or in an electrical washing machine.

In a conventional liquid agitating device comprising a rotating shaft for driving an agitating vane and extended through an agitating tank, it is necessary to use a liquid sealing means such as an oil seal, a mechanical seal, etc., in order to prevent the liquid in the agitating tank Ifrom leaking out of the tank along that portion of the shaft which extends through the tank.

Such liquid sealing means, however, becomes rapidly degraded due -to a slight vibration of the -shaft or to pulverized solid particles contained in the liquid to be agitated, which results in a leakage `of the liquid, thereby adversely affecting the function of the liquid sealing means.

In order to obviate such disadvantages, it has been proposed to suspend vertically a long shaft from the upper part of the agitating tank and secure an agitating vane to the lower end of the shaft so as to immerse the agitating vane in the liquid to 'be agitated, thereby omitting that portion of the rotating shaft which extends through the agitating tank. Such device, however, has disadvantages that the long driving shaft journaled in the bearing causes wearing of the shaft very soon, and that presence of a transmission mechanism for driving the long shaft including an intermediate bearing, gears, pulleys, belts, etc., reduces the life of a driving motor, increases the installation cost and lowers the trans-mission efiiciency.

Any similar conventional device has disadvantages that the agitating tank has to be provided at its outside with extra equipment, and that an agitating power loss becomes large.

The object of the present invention is to obviate the above mentioned disadvantages and provide a liquid agitating device adapted -to prevent the liquid being agitated from leaking out of the agitating tank. Another object of the present invention is to prevent the outside air from penetrating into a hermetically sealed vacuum agitating tank and having the additional advantage that reduction of a space occupied by the device and running costs thereof is possible.

For a better understanding of the invention, reference is taken to the accompanying drawing, in which a single ligure is a longitudinal sectional View showing an lembodiment of the present invention.

Referring to the drawing, 1 represents a motor casing which is `open at its inner end `and provided at its inner peripheral edge with an annular step 2. To this annular step 2, several supporting plates 3 are welded. An annular stator core 4 of an axial air gap type induction motor is secured to the supporting plates through the aid of several bolts 7 which extend through several -cavities S formed at given intervals along the outer periphery of the outside wall of the .motor casing 1 and also through washers `6. A stator coil 8 of the axial air gap type induction motor is wound around the stator core 4. Thus, the motor casing 1 encloses therein the stator core 4 and the stator coil 8 of the axial air gap type induction motor.

The motor casing 1 is provided at its center part with a center projection 9 which is integral with the casing 1.

3,279,765 Patented Oct. 18, 1966 ICC An end plate 10 bears upon the inner end of the center projection 9, Iwhilst a sealing partition Wall plate 11 of nonmagnetic anti-corrosion material bears closely upon the opposite side of the end plate 10 and upon the inner periphery of the casing 1 and the inner end of the stator core 4.

A bore 12 is drilled through the center projection 9 of the motor casing 1. The outer part of a fixed shaft 15, having an intermediate fitting'ange 14 which is integral with the Ishaft 15, extends through a packing 13, the partition wall plate 11, the end plate 10 `and through the bore 12. The outer end of the fixed shaft 15 has formed at its outer periphery threads 16 for threaded engagement with a Washer 19 and a nut 17. The nut and washer rest in a cavity 18 formed at the center of the outside wall of the motor casing 1. An internal axial hole 20 is formed along the axis of the fixed shaft 15. The axial hole 20 is hermetically closed by a sealing plug 21 detachably threaded into the outer end of the axial hole 20.

Provision is made for a rotating body 22 which has formed on its outside surface `an annular step 23. An annular rotor core 26, having squirrel .cage type inner and outer copper rings 24 and 25 of the axial air gap type induction motor, is secured to said annular step through several supporting plates 27, welded at given intervals along the inside surface of the annular rotor core 26, by means of several bolts 28. The outside exposed surfaces of the rotor core 26 and of the inner and outer copper rings 24 and 25 and also the inner and outer circumferences of the latter rings are painted with an anti-corrosive paint or covered with an anti-corrosive sheet metal 29. The rotor core 26 is arranged in opposition to the stator core 4 to form an air gap 30 therebetween.

The rotating body 22 is provided at its center part with a boss portion in lwhich a bearing 31 is fitted to form the air gap 30, the axial length of which i-s adjusted with the aid of a few washers 33. The bearing 31 is provided `at its outer peripheral edge bearing upon the intermediate fitting flange 14 with several notches 34. Clamping pieces '35 in engagement with several notches 34 serve to clamp the bearing 31, the clamping pieces 35 being fastened to the outside surface of the center boss 32 with the aid of washers 36 and bolts 37. As a result of this, the bearing 31 can be made integral with the rotating body 22 and be rotatably mounted around that portion of the fixed shaft 15 which lies inside the intermediate fitting flange 14.

The'center boss 32 of the rotating body 22 is Iformed at its inside with a .stepped part 38 having a cylindrical portion 39 projected from the stepped part 38. The fixed shaft 15 is formed at its inner end with a reduced portion 41 extending through the cylindrical portion 39. The reduced portion 41 is formed with several holes 40 communicated with the axial hole 2t) of the fixed shaft 15. The reduced portion 41 is formed around its end portion with :threads 42 which are brought into threaded engagement with a nut 45. The nut 45 bears upon the inner end of the Icylindrical -portion 39 through a washer 44 and several adjusting washers 43 in order to prevent removal of the rotating body 22. The adjusting washers 43 serve to set the rate of axial displacement of the rotating body 22.

Around the circumference of the stepped part 38 is fastened .an agitating vane 46 by means of a lock pingroove connection 47 and 48. The groove 48 is formed at the center step of the agitating vane 46. Provision is made for a lcap nut 49, having a threaded portion 50 which is in mesh with the outside threads of the cylindrical portion 39 such that the cap nut 49 may be made integral with the rotating body 22.

The cap nut 49 is provided at its center with a tapped hole 51 into which a Ilocking bolt 52 is detachably 3 threaded. The center cavity 18, formed in the outside wall of the motor casing 1, is closed by an end plate 53 fastened to the outside wall of the motor casing 1.

The motor casing 1 is formed at its inner peripheral edge with `a flange 54. An agitating tank Wall 55 includes an annular fitting frame 57 Welded to the inner circumferential edge of the tank wall 55 to form an opening 56. To the annular fitting frame S7 is welded an annular flange 58 which is L-shaped in section and arranged in opposition to the flange 54. The flanges 54 and 58 are clamped together with a gasket 59 and the partition wall plate 11 by means of several bolts 60 so that the agitating vane 46 may be located in the agitating tank 55.

In operation of the device constructed as iabove inentioned, the rotor core 26 is caused to rotate by the magnetic induction effect of the stator core 4, which results in a rotation of the rotating body 22 which is integral with the -r-otor core 26 tand journalled about the bearing 31. At the saine time, the agitating vane 46 which is integral with the rotating body 22 is caused to rotate about the fixed shaft 15, thereby agitating the liquid in the agitating tank 55.

The stator core 4 and the stator coil 8 in the motor casing 1 are separated and protected from the liquid to be agitated in the agitating tank 55 by means of the partition wal-l plate 11. This also permits a safety operation to be continued and the motor casing 1 to be hermetically sealed from the wall of the agitating tank 55, without leaking the liquid to be agitated in the agitating tank 55 out Aof the motor casing 1. Thus, the invention provides a reliable way of preventing leakage of the liquid in the Iagitating tank 55 Without it being necessary for any sealing means such as an oil seal, mechanical seal, etc. to be used in order to prevent the leakage of liquid as is ordinarily found in the conventional device.

Moreover, since the agitating vane 46 is made integral with the rotating body 22, having the rotor core 26, by means of the cap nut 49, it is possible to replace the agitating vane 46 with any vane suitable for the kind of the liquid to be agitated. As explained with reference to the above embodiment, a hollow shaft having an integral axial hole formed therein is used as the fixed shaft 15. The fixed shaft is detachably provided :at its outer and inner ends With the sealing plug 21 and the sealing bolt 52, respectively. Thus, if ia clean liquid is used as the liquid to be agitated and the outer sealing plu-g 21 is threaded into the outer end of the axial shaft 15 and the inner sealing bolt 52 is removed from the cap nut 49, the pressure difference produced during the 'agitation of the liquid renders it possible to effect Aa forced circulation of the liquid from the tapped hole 51 through the inner axial hole formed in the fixed shaft 15, the transverse hole 40, a radial air gap a formed between the fixed shaft 15 and the bearing 31, a slight air gap b formed between the intermediate tting flange 14 and the bearing 31 and the air gap 30 formed between the partition wall plate 11 and the outer end surface of the rotor core 26 to the agitating tank 55. If a slurry containing foreign solids, crystals, etc. is used as the liquid to be agitated and the outer sealing plug 21 is removed from the end of the fixed shaft 15 and the sealing bolt 52 is threaded into the cap nut 49, the clean liquid may be fed into the inner axial hole 20' in the fixed shaft 15 to effect a forced circulation of the clean liquid. This considerably facilitates the lubrication for the bearing 31. Thus, it is possible to lubricate the rotating surface which lies between the fixed shaft 15 and the bearing 31 for the agitating vane 46 with the raid of the liquid to be agitated or any other clean liquid, thereby maintaining a smooth rotation of the agitating Vane 46. This lubrication serves to prevent Wear of the -rotating members resulting from overheating at the rotating surface which lies between the fixed shaft 15 and the bearing 31. Even as the bearing 31 becomes worn and the rotor core 26 comes into contact with the partition wall plate 11 and there is tendency to stop the rotation of the agitating vane i 46, the stator core 4 and the fixed shaft 15 together with the partition Wall plate 11 assure a hermetical seal against leakage of the liquid from the agitating tank 55.

The above mentioned rotating means according to the invention in which use is made of an axial ai-r gap type induction motor to drive an agitating vane without causing any leakage of the liquid is far superior to any conventional rotating means in which a rotating shaft extends through an agitating tank. The advantage of the device according to the invention can easily be understood if compared ,with the conventional device wherein use is made of ia radial air gap type induction motor as a rotating means. If the radial air gap type induction motor is used as the rotating means, that portion of the motor Which projects out of the agitating tank becomes long, so that it is necessary to reinforce the fitting part of the agitating tank. Moreover, a number of means are required to lubricate and cool the bearing. In the conventional device, both the stator `and the rotor rotating in the stator are immersed in the liquid, so that the power required to revolve the rotor in the stator in the liquid is not utilized to agitate the liquid, thereby increasing the power loss. Contrary to this, the present invention has advantages that the dimension of the portions outside the agitating tank 55 can be made smaller by several times, i.e., one tenth, lthan required for the radial air gap type induction motor. Moreover, the present invention makes it possible to prevent the outside air from penetrating into a her-l metically sealed vacuum tank used as the agitating tank, which could not be attained by any conventional shaft sealing device. The overall efficiency of the device according to the invention in which all of the rotating members are immersed in the liquid is several times that of the conventional agitat-ing device wherein use is made of the radial air gap type induction motor for the purpose of driving the agitating vane through a long shaft and a transmission means arranged outside the agit-ating tank. The partition Wall yplate 11 inserted in the air gap 30 formed between the stator core 4 and the rotor core 26 is made of a material which is non-magnetic and has a high resistivity in order to limit the flux density and therefore Idecrease the eddy current loss to an extremely small value. The rotor core 26 is of a squirrel cage type construction in which laminated silicon sheet steel is combined With a copper bar and -a copper ring, which results in a high output agitation in an extremely efficient manner and a continuous agitation in a large type agitating tank of the order of '100 tons.

ln carrying out the invention into effect, if a vacuum tank or a high pressure tank is used as the agitating tank 55, provision is made at the inside of the opening and at the outer periphery of the inner end of the projection 9 of the motor casing 1 of annular lining plates 61 and 61 made of non-magnetic material such as SUS material, etc., and Welded to the partition Wall plate 11 for the purpose of reinforcing the latter.

If use is made of a hot liquid heated to a high temperature of the order of C.-250 C. as the liquid to be agitated, the partition wall plate 11 is painted at its inner surface with a heat insulating material such as silicon rubber and the motor casing 1 is divided into two chambers in which cooling Water is caused to circulate through an inlet 62 and an outlet 63, thereby protecting the stator coil 8 from overheating.

As above mentioned, the invention makes use of a rotating shaft which does not extend through an agitating tank and may be applied to a vacuum tank and a high pressure tank without allowing leaking liquid out of the tank and without allowing the outside air into the tank. The invention also makes use of a rotating means and also an axial air gap type induction motor so as to provide an agitating device which is compact in construction and highly efficient in agitating operation, `which could never be attained by any conventional rotating means.

Though the invention is described by means of an ernbodiment as shown in the drawing, yet Various modifications can of course he made without departing from the scope of the invention.

What we claim is:

1. A liquid agitating device comprising a casing, a stator core and stator coil of an axial air gap type induction motor enclosed in the casing, a partition wall plate made of a non-magnetic and non-corrosive material and closely fastened to the inside surface of the casing, a fixed shaft secured at its outer portion to the center part of the casing, an agitating vane journalled about a bearing on the inner portion of the fixed shaft and including a rotor core arranged in opposition to the stator core to form an air gap therebetween, means passing through the center of said xed shaft for introduction of a lubricating and cleansing fluid to said bearing, and an agitating tank, the peripheral edge of the casing and the circumferential edge of an opening formed in the agitating tank being secured together such that the agitating vane is positioned in the agitating tank.

2. A liquid agitating device comprising a casing, a stator core and stator coil of an axial air -gap type induction motor enclosed in the casing, a partition Wall plate made of a non-magnetic and non-corrosive material and closely fastened to the inside surface of the casing, a Xed shaft secured at its outer portion to the center part of the casing, a rotating body including a rotor core and journalled through a bearing about an inner portion of the fixed shaft, an internal axial hole formed through the axis of said xed shaft for the introduction of lubricant to lubricate and cleanse said bearing, said lubricant being moved about the bearing by a pressure diiferential produced during agitation of the liquid to effect a forced circulation of the liquid, said rotor core being arranged in opposition to the stator core to form an air gap therebetween, and an agitating vane secured to the rotating body, and an agitating tank, the peripheral edge of the casing and the circumferential edge of an opening formed in the agitating tank being secured together such that the agitating vane is positioned in the agitating tank.

References Cited by the Examiner UNITED STATES PATENTS 742,385 10/ 1903 Blaisdell 259-23 FOREIGN PATENTS 531,130 10/1954 Belgium. 897,836 11/1953 Germany.

WALTER A. SCHEEL, Primary Examiner.

IRVING BUNEVICH, WILLIAM I. PRICE,

Examiners. I. R. JENKINS, Assistant Examiner. 

1. A LIQUID AGITATING DEVICE COMPRISING A CASING, A STATOR CORE AND STATOR COIL OF AN EXIAL AIR GAP TYPE INDUCTION MOTOR ENCLOSED IN THE CASING, A PARTITION WALL PLATE MADE OF A NON-MAGNETIC AND NON-CORROSIVE MATERIAL AND CLOSELY FASTENED TO THE INSIDE SURFACE OF THE CASING, A FIXED SHAFT SECURED AT ITS OUTER PORTION TO THE CENTER PART OF THE CASING, AN AGITATING VANE JOURNALLED ABOUT A BEARING ON THE INNER PORTION OF THE FIXED SHAFT AND INCLUDING A ROTOR CORE ARRANGED IN OPPOSITION TO THE STATOR CORE TO FORM AN AIR GAP THEREBETWEEN, MEANS PASSING THROUGH THE CENTER OF SAID FIXED SHAFT FOR INTRODUCTION OF A LUBRICATING AND CLEANSING FLUID TO SAID BEARING, AND AN AGITATING TANK, THE PERIPHERAL EDGE OF THE CASING AND THE CIRCUMFERENTIAL EDGE OF AN OPENING FORMED IN THE AGITATING TANK BEING SECURED TOGETHER SUCH THAT THE AGITATING VANE IS POSITIONED IN THE AGITATING TANK. 